Method of hardening metal strips



'Feb. 11, 1930. c. SCHUMACHER METHOD OF HARDENING METAL STRIPS OriginalFiled May 5, 192'! ATTORNEY Patented Feb. 11, 1930 UNITED STATES vPATENT; OFFICE CONRAD SGHUMACHER, OF LYNNIBROOK, NEW YORK, ASSIGNOR TOAUTOSTROP PAT- .ENTS CORPORATION, OF DOVER, DELAWARE, A CORPORATION OFDELAWARE METHOD OF HARDENING METAL STRIPS Application filed May 3, 1927,Serial No. 188,427. Renewed. July 2, 1929.

The invention relates to an improved method of hardening or chillingcontinuous lengths of heated steel strips as they pass from a heatingfurnace.

An object of the invention isto maintain a heated strip in contact withsuccessive chilling or cooling plates as the strip travels from afurnace to chill the strip to approximately a desired temperature, andat the same time to keep the strip in a flat condition and prevent itfrom bending or warping while chilling and to maintain. said chillingplates at approximately a constant temperature.

Another object of the invention is to chill diflerent portions of theheated strip to different degrees of hardness as the strip travelsbetween the chilling plates. A feature of the invention is that theharder portion or portions of the strip may be ground for producing oneor more cutting edge or edges thereon, and a soft portion may beperforated, the invention being particularly applicable in themanufacture of safety razor blades, and other tools and articles.

The invention embodies novel features of improvement more fullyhereinafter set forth and then pointed out in the claims.

Reference is to be had to the accompanying drawings forming a parthereof, wherein Fig. 1 is a perspective view illustrating an apparatusadapted for carrying out the invention;

Fig. 2 is an enlarged longitudinal section through the steel-chillingdevices, substantially on the plane of line 2, 2, in Fig. 3;

Fig. 3 is a cross section substantially on line 3, 3, in Fig. 2;

Fig. 4 is a perspective detail view, partly in section, illustratinglower chilling plates;

-Fig. 5 is a detail perspective view illustrating superposed plates, and

Figs. 6, 7 and 8 are detail perspective views of modified forms ofchilling plates for chilling strips to different degrees of hardness indifl'erent parts of the strips.

- Similar numerals of reference indicatecorresponding parts in theseveral views.

The numeral 1 indicates a furnace which may be of any suitable ordesired character adapted to heat a metal strip A to an appropriatetemperature, such as a relatively thin flexible strip of steel, as thesame travels through the furnace. The strip may be PIO'. pelled throughthe furnace and wound by means of areel B which, may be operated atdesired speed in any suitable way, such as by means of belt and pulleyC, D. Other suitable propelling means for strip A may be used. Closelyadjacent to the furnace are chilling plates 2 and 3 superposed andbetween which the strip A may be propelled. By preference thereareseveral pairs of chilling plates 2 and .3 spaced apart along the stripwith spaces at t between each pair of plates, as indicated in Fig. 2.The strip A rests upon the lower plates 2 and the upper plates 3 restupon the strip so that the respective plates are in contact with thestrip. The chilling plates 2 are supported on the top plate 5 of a boxor tank 5 so as to be cooled or chilled by contact therewith. The upperpart of box 5 is shown provided with side walls 5* which retain theplates 2 and 3 from lateral displacement. T 0 keep the plates 2 and 3 intheir proper positions so that they will not be displaced lengthwiseduring travel of strip A therebetween the plates 2 are shown providedwith lateral projections 2 engaging the metal at adjacent sides ofrecesses 5 in the side walls 5 of box 5, and the upper plates 3 aresimilarly provided with side projections 3 to engage the metal at thesides of said re cesses, (Figs. 4 and 5).. The arrangement describedpermits the chilling plates to be removed and replaced as required forready application of strip A between the plates. The box 5 is supportedin any suitable manner, as upon a table or support 6 shown havthe uppersurface to direct. streams of cooling fluid E against the boxtop 5,(Fig. 2). The pipe 8 may have a single fluid delivery slot if preferred.The inner end 8 of pipe 8 is shown closed to assure the flow of the jetsor streams of fluid therefrom. The ipe 8 may be supplied with fluidunder esired pressure in any suitable way, such as by a pump from asource of supply. The waste cooling water or fluid from pipe 8 will flowinto the box or tank 5 and an overflow outlet pipe is indicated at 9 forthe box which may lead to a sewer or other suitable place, or the wateror other fluid may be re-pumped from the box 5 back to the same in acontinuous way.

A tank 10 for cooling water or other fluid restsupon the upper chillingplates 3, the bottom 10 of which'tank is preferably flexible sothatthrough the fiexibillty of said bottom each of the upper chillingplates 3 may be independently pressed by means of a weight thereon tokeep each plate in desired contact with strip A. For such purposepressure plates 11 within tank 10 are located over the correspondingchilling plates 3 to pressthereon, saidplates 11 preferably havingspaced feet 11 to bear on the tank bottom 10 in spaced relation so asnot to interfere with the distribution of cooling -fluid on said bottom.Said plates 11 are shown pivotally connected at 12 with rods13 dependingfrom arms 14, to which arms the rods 13 may be attached by meansofsscrews 15. The arms 14 are pivotally supported upon rod 16 which iscarried by brackets or uprights 17 secured on table 6, whereby the armswith the respective plates 11 may be swung away from tank 10 and theplates may be returned thereto as required. Suitable weights 18 arecarried by the arms 14 and may be detachably secured thereto by means ofscrews 19.

- When the parts are in the positions illustrated the weights 18 willpress through the plates 11 upon the flexible bottom 10 of tank 10 toindividually press the corresponding underlying upper chilling plate 3against strip A. The chilling water or other fluid may be supplied tothe tank 10.by means of a flexible hose or other conduit 20 from asuitable source of supply, and at a desired height the tank is providedwith an outlet pipe at 21- which may deliver the overflow cooling fluidfrom the tank into the pipe 9 or to any other receptacle,2or forrepumping to the tank. When it is desired to replace a strip A betweenthe chilling plates the arms -14 may be swun'g outwardly carrying thecorresponding weight and the plates 11 away from the box so that thelatter may be lifted off of the lates 3, and said plates 3 may beremoved or adjustmentof a new strip 'A over the plates2, and ,then saidplates and other parts may be replaced for chilling said strip. Thechilling tank .10 is shown provided with deflector p1ates"1O thatexseveral pairs of plates 2 and 3 independent of each other and spacedapart a suitable distance'each pair of plates will operate on strip Aindependently of any other pair of plates and thereby bending or warpingof strip A as it passes between the plates is prevented, because eachtop-plate 3 may bear independ ently upon relatively short portions ofthe strip, as distinguished from a single pair of chilling plates whichare of suflicient length as to extend completely along the chilling zoneof a heated strip and which have heretofore been liable to warp-becausesubjected to heating on their inner surfaces against the heated stripand to cooling on their outer surfaces with a considerable difference intemperature between the two end portions. lVhile the contact of theheated strip A with the adjacent surfaces of the chilling plates 2 and 3tends to heat the"plates the continuous supply of cooling fluidmaintained at a substantially even temperature will keep each pair ofplates at substantially relative temperatures-so that the strip willemerge from between the last pair of plates at the desired hardenedstate or condition.

All of the plates 2 and 3 may have complete surfaces in contact withstrip A so as to give a similar degree of hardness to the stripthroughoutits full width. For some purposes it is desired to producedifferent degrees of hardness along different portions of strip A andthis may be accomplished by starting the initial chilling of the stripat one portion (where it is to be the hardest) ahead of another portionof the strip that is to have a' less degree of hardness, so that theinitial chilling of the latter portion of the strip is startedsubsequently to the initial chilling of the firstna'med portion of thestrip. In the example illustrated the plates 2 and 3 next adjacent tothe furnace are provided with recessedportions 2', 3, respectively, therecess of one. plate opposing the recess of the opposite plate, asillustrated in Figs. 2 and 5, such recesses extending lengthwise of thecorresponding lates and opening through the end ofsuc plate nextadjacent to the furnace, (Figs. 4 and 8). In case it is desired that theedge portions of strip A shall have extending lengthwise of the platesin a central position. If it be desired that one edge portlon of thestrip be hardened more than another edge portion of the strip therecesses 2 and 3' of the corresponding plates will be located adjacentto the edge of the strip to have the lesser degree of hardness, (Fig.6). In case it be desired thatthe hardness of the strip A shouldgradually increase in the direction from one edge toward the other therecesses 2 and 3 may be arranged as illustrated in Fig. 7, that is tosay the recesses will extend substantially across the plates 2 and 3,with the widest extent at the ends next adjacent to the furnace and theedge of the recess at 2" may extend in a diagonal or other angulardirection across the plates from at or near one edge to or toward theother. If it be desired that the strip shall have its central portionhardened to the greatest degree and its two edge portions hardened to alesser degree the plates 2 and 3 may have two spaced recesses, asindicated at 2' in Fig. 8, along the sides of the plates, leaving thecentral portion, such as at 2, to bear u on the stri at the endsadjacent to the urnace. When the heated traveling strip first engagesthe plates 2 and 3 that are next adjacent to the furnace the portion ofthe strip that first contacts with said plates will receive an initialand continuing chilling and the portion of the strip at one side of thefirst named portion and that passes between the opposing recesses 2, 3of the plates will be reduced or will drop slightly in temperature belowits, temperature as it emerges from the furnace, (by reason ofatmospheric cooling), without chilling contact with the plates,,and whensuch portion of the strip engages the chilling surfaces of the platessuch portion of the strip will be initially chilled, and the chilling ofall por tions of the strip will continue simultaneously as it travelsbetween the successive pairs of plates. The portion of the strip thatlast contacted with a pair of chilling plates will be hardened to a lessdegree than the portion of the strip which first or initially contactedwith a pair of chilling plates.

During the rogress of the heated strip between the chil ing platesitwill be gradually reduced in temperature to the degree desired whenitemerges from between the plates, and may be left to cool in thatconditlon, or the strip may be tempered by reason of the desired degreeof residue heat still in the strip. In Fig. 1 tempering plates 22, 23are shown supported upon table 6 in such position that the strip A maypass between said plates, the upper plate 23 resting upon the strip andkeeping it in contact with the plate 22 as the strip travels between theplates. Said tempering plates may be heated to any desired temperatureby any suitable means, such as by means of an electrical heater,indicated generally at 24.

By the means described strips of steel having different degrees ofhardness may be'utilized for production of tools or implements forvarious purposes. For instance, razor blades may be made from the stripA with the longitudinal central portions of the blades of less hardnessthan the edge portions in accordance with Fig. 4, or with one edgeportion of less hardness than the otheredge, in accordance with Fig. 6,so that the harder portion or portions of the blades may be providedwith cutting edges, and apertures may be punched with facility andeconomy in the less hardened or softer portion of the strip.Furthermore,saws may be made from some of the strips with the teeth outalong the hardened edge portion, leaving the other portion of the sawsof less degree of hardness.

Having now described my invention what I claim is 1. The method ofhardening a strip of metal consisting in heating the strip to a desiredtemperature, initially chilling one portion of the strip before chillinganother portion thereof that is located at one side of the first namedportion, subsequently chilling both said portions simultaneously, andpropelling the strip as it hardens.

2. The method of hardening a strip of metal consisting in heating thestrip to a desired temperature, initially chilling a portion of thestrip, and causing the temperature of another portion of the strip atone side of the first named portion to be reduced by atmospheric coolingbelow its temperature as it emerges from the heating means, subsequentlychilling both said portions simultaneously, and propelling the strip asit hardens.

3. The method of hardening a strip of metal consisting in heating thestrip to a de-' sired temperature and passing the strip between chillingsurfaces, initially chilling one portion of the stripbefore chillinganother portion that is located at one side of the first named portionthereof, and subsequently chilling both said portions.

CONRAD SCHUMACHER.

